High Temperature Superconducting Wire Research Articles

A Review of the Ion Beam Assisted Deposition Researches towards Industrialization for the Second Generation High Temperature Superconducting Wire Fabrication

on beam assisted deposition (IBAD) is an important technique to fabricate the second generation high temperature superconducting (2G HTS) wires. Among the fabrication routes of 2G HTS long wires, IBAD route achieved the best performance in recent years. IBAD was adopted in this field in 1991 to obtain biaxially textured buffer layers, which helped to deposit high quality YBCO superconducting films on metallic substrates for the first time. Series of experimental and industrial researches on IBAD were carried out by many groups worldwide. And in the researches lasting for over two decades, the focused material for IBAD was changed from Yttria-Stabilized Zirconia (YSZ), Gd2Zr2O7 (GZO) to MgO. In this paper, the research progresses and the main achievements were briefly reviewed.

Angular Dependence of Transport AC Losses in Superconducting Wire with Position-Dependent Critical Current Density in a DC Magnetic Field

Transport AC losses play a very important role in high temperature superconductors (HTSs), which usually carry AC transport current under applied magnetic field in typical application-like conditions. In this paper, we propose the analytical formula for transport AC losses in HTS wire by considering critical current density of both inhomogeneous and anisotropic field dependent. The angular dependence of critical current density is described by effective mass theory, and the HTS wire has inhomogeneous distribution cross-section of critical current density. We calculate the angular dependence of normalized AC losses under different DC applied magnetic fields. The numerical results of this formula agree well with the experiment data and are better than the results of Norris formula. This analytical formula can explain the deviation of experimental transport current losses from the Norris formula and apply to calculate transport AC losses in realistic practical condition.

Bi2-xHgxSr2-yBayCa2Cu2O10/Ag Sheath HTSC Wires, (Hg, Ba) Substitution Effect on the Critical Temperature

Bi2-xHgxSr2-yBayCa2Cu3O10 High Temperature Superconductor (HTSC) has been prepared as a pellet by solid state reaction with a certain substitution percentages (0,0.05,0.1) of Hg and Ba substitution instead of Bi and Sr respectively. Then, HTSC wires were fabricated from the prepared superconductor pellets using powder in tube (PIT) method utilizing silver as the tube material. The prepared wires are of three types; with monofilament MOF, 9 multifilament core 9MF and 81 filaments core(81MF). Several cycles of mechanical drawing and rolling process performed to the starting silver tube of 0.4cm diameter and 5cm length to minimize the filament diameter. The average filament diameter with 81MFC wire was about 25μm measured with an optical microscope.Tc critical temperature for superconductivity is measured for the pellets and wires using four point probes techniques. These results show that the substation Bi by Hg give a rise to the superconductor to improve highly Tc, while substitution Sr with Ba lowers Tc.substitution of 0.05, 0.1 Hg to the composition Bi2-xHgxSr2-yBayCa2Cu3O10 will raise the transition temperature (Tc). Also substitution of Sr by Ba decreases the transition temperature (Tc), Hg(0.05 – 0.1) substitution still raise Tc after substitution of Ba with (0.05 – 0.1). High – Tc phase (2223), 2221 phase in B-2223 system and the addition of Ag to silver sheaths and a small amount of impurity phases appear in the result of XRD analysis.

Second Generation Wire Development at AMSC

AMSC has established a Second Generation (2G) High-Temperature Superconductor (HTS) wire manufacturing technology based on the Rolling Assisted Biaxially Textured Substrate and Metal Organic Deposition processes. AMSC's 2G wire (Amperium) has been used by a wide range of customers for development and testing of initial commercial HTS-based applications. Although the Amperium wire properties and quantities satisfy the requirements for these initial projects, improvements in critical current, field performance, and cost are beneficial for large-scale commercial and military applications. As Amperium wire manufacturing continues to ramp up, AMSC's R&D program has focused on increasing critical current, and the development of nonmagnetic substrates. The R&D process developed for a single-coat, 1.2 μm YBCO film has been transferred to production-scale equipment, resulting in the first Amperium wires with critical currents reaching 500 A/cm-w (77 K, self-field) in production length. A nonmagnetic substrate, which minimizes ferromagnetic substrate losses in ac cable applications, has been produced in R&D lengths and demonstrated in an Amperium cable wire.

Designed 3D architectures of high-temperature superconductors

Self-supporting superconducting replicas of pasta shapes are reported, yielding products of differing 3D architectures. Functioning high-temperature superconductor wires are developed and refined from replicas of spaghetti, demonstrating a unique sol-gel processing technique for the design and synthesis of novel macroscopic morphologies of complex functional materials.

Design and AC Loss Analysis of a 22.9 kV/50 MVA Class Triaxial HTS Power Cable

Recently, triaxial high temperature superconducting (HTS) power cables have become a mainstream design in the development of HTS cables because of several advantages, such as the reduced amount of HTS wire, low leakage fields, and compactness, when compared with other types of HTS cable. Unlike the AC loss from other types of HTS cable, the AC loss from the triaxial HTS cable is influenced by the magnetic fields of other phases, as the triaxial HTS cable does not have a shield layer between the phase conductors. The authors have designed a 22.9 kV/50 MVA class triaxial HTS power cable. The AC loss and the magnetic characteristics of the triaxial HTS power cable are analyzed using the Comsol program, a commercial finite element method. To confirm the characteristics of the triaxial HTS power cable by wire type, the characteristics of two wire types were applied to the FEM model.

초전도 한류기 설계 검증을 위한 초전도 한류 모듈 단락 특성 시험

KEPCO Research Institute has been researching a Superconducting Fault Current Limiter (SFCL) which is considered one of solutions of fault current problems with Korea Institute of Machinery & Materials (KIMM) and Hanyang University since 2011. In this paper, we fabricated a current limiting module and conducted electrical short circuit tests for checking the validity of the transmission level SFCL design. Based on the short circuit characteristics of the second generation High Temperature Superconductor (HTS), we analyzed the short circuit characteristics of 3 parallel connected superconducting wires. The structure of the HTS wire is as follows: the stainless steel stabilizer of <TEX>$100{\mu}m$</TEX> is laminated on the superconductor layer and under the substrate, both of which are electrically jointed with solder. We fabricated the current limiting module which has 40 series and 6 parallel connections and studied the short circuit characteristics of the module under various voltage levels.

Second-Generation High-Temperature Superconductor Wires for the Electric Power Grid

Superconductors offer major advantages for the electric power grid, including high current and power capacity, high efficiency arising from the lossless current flow, and a unique current-limiting functionality arising from a superconductor-to-resistive transition. These advantages can be brought to bear on equipment such as underground power cables, fault current limiters, rotating machinery, transformers, and energy storage. The first round of significant commercial-scale superconductor power-equipment demonstrations, carried out during the past decade, relied on a first-generation high-temperature superconductor (HTS) wire. However, during the past few years, with the recent commercial availability of high-performance second-generation HTS wires, power-equipment demonstrations have increasingly been carried out with these new wires, which bring important advantages. The foundation is being laid for commercial expansion of this important technology into the power grid.

Novel tri-modal defect structure in Nb-doped MOCVD Y Ba2Cu3O7: a paradigm for pinning landscape control

Immobilization of vortices, or flux pinning, is both an enduring scientific issue and one of the most important problems in optimizing high temperature superconductors (HTSs) for commercial use. Here, we demonstrate a practical approach to the creation of a multi-modal flux pinning landscape in Y Ba2Cu3O7 (YBCO) films employing an industrially scalable metal–organic chemical vapor deposition technique. Through controlled additions of Nb, we have achieved a novel distribution of crystallographic defects that immobilize (pin) vortices in the YBCO matrix. That is, with only the addition of a single dopant element, a tri-modal, non-superconducting defect structure is induced that threads through the YBCO matrix laterally (parallel to the ab planes of YBCO), vertically (parallel to the YBCO c-axis), and isotropically in the form of random spherical defects. For optimally doped samples, the influence of these multi-modal nanocrystalline defect structures on the flux pinning properties manifests itself as a significant improvement in the critical current density (Jc) for all magnetic field orientations. The results demonstrate the possibility of achieving an ideal flux pinning landscape (from an orientation and strength viewpoint), which permits the design of HTS wires with fully-tunable properties by processes suitable for large-scale manufacturing.

Design and Tests of Prototype Hybrid Superconducting Fault Current Limiter With Fast Switch

This paper deals with design and operating tests of prototype hybrid superconducting fault current limiter (SFCL) which is series connected non-inductive solenoid resistive coil and asymmetric non-inductively wound coils. The role of resistive SFCL is for reducing the fault current in the first swing. Moreover, resistive SFCL can reduce a load of dielectric strength in hybrid SFCL. Two kinds of high temperature superconductor (HTS) wires were used to fabricate asymmetric HTS coil. These HTS wires had different quench characteristics such as different critical current and n-value. Unbalanced current distribution between two HTS wires in the asymmetric HTS coil during the fault should occur. Thus, the asymmetric HTS coil generates impedance and repulsive force from magnetic flux. The finite element method was performed to calculate maximum repulsive force. From experimental tests and FEM simulation results, proper combination of HTS wires and configuration of asymmetric HTS coil with fast switch were determined to increase maximum repulsive force. Also, the prototype hybrid SFCL with fast switch was fabricated and performed.

AC loss measurements in pancake coils wound with 2G tapes and Roebel cable: dependence on spacing between turns/strands

AC loss measurements in five single pancake coils wound with 4 mm wide commercial high temperature superconductor wires were carried out to investigate the dependence of coil AC loss on separation between the superconductor layers in the neighbouring coil turns (g) and coil turn number (N) for a given number of ampere-turns NI. The highest frequency was set at approximately 1 kHz. The AC losses measured at different frequencies agreed well with each other. AC loss in the coils with the same N increases with decreasing g. When g is increased to 1.5 times the tape width (6 mm), the loss level is similar to that in an isolated wire. Transport AC loss per unit length in the pancake coils increases with increasing turn number. However, when g is increased to 1.5 times the tape width, the loss level in the coils with different turn number is almost the same. This indicates that, at the same NI, a coil with greater N is advantageous, even considering the conductor length difference. Therefore to achieve a given level of NI for a coil and minimize AC loss, we should favour coils with more turns. Coil AC loss can be measured using voltage taps attached to copper blocks outside a coil with reasonable accuracy. This is important for measuring AC loss in a coil with a complicated structure where voltage taps are not able to be attached inside the coil. AC loss in a nine-turn pancake coil wound with a 5 m long 9/2 Roebel cable (i.e. with 9 mm × 2 mm width strands) was measured using voltage loops arranged in each Roebel strand in the central turn of the coil. The AC loss in the coil was compared with two straight 9/2 Roebel cables with and without spacing between the strands. The combination of inter-strand spacing and turn spacing is an effective way to reduce AC loss in a single pancake coil wound with a Roebel cable.

New Material Requirements for Superconductor Grid Technology

Superconductor ac and dc cables, fault current limiters and wind turbine generators offer solutions to key challenges in modernizing electric power infrastructure around the world. High critical current Jc is an essential requirement for the practical commercial operation of such systems. High temperature superconductor (HTS) wires have met the basic Jc requirements, and some initial systems have been successfully installed in the power grid. From an applications perspective, further progress in increasing the superconductor critical temperature Tc and critical current Jc could open up an even broader impact. However, thermal fluctuations and the resulting flux creep depress critical current, creating a trade-off between higher temperature and higher critical current. The origins of this trade-off are discussed. The YBCO material used in today's second generation HTS wires strikes a good compromise between these competing effects, and because of the flux creep problem, applications needs call for further research to be focused more on increasing Jc than on increasing Tc.

B2223 High Temperature Superconductor Wires in Silver Sheath, Filament Diameter Effect on Critical Temperature and Current Density

B2223 High Temperature Superconductor (HTSC) has been prepared as a pellet by solid state reaction. Then, HTSC wires were fabricated from the prepared superconductor using powder in tube (PIT) method utilizing silver as the tube material. Superconductor powder was packed in the pure silver tube of about 4.5mm diameter, and 50mm long. The prepared wires are of three types; with monofilament MOF, 9 multifilament core (9MF) and 81 filaments core(81MF). Several cycles of mechanical are drawing and rolling process performed to the starting silver tube of 0.4cm diameter and 5cm length and 0.35mm thickness to minimize the filament diameter. The average filament diameter of MoC with 0.7mm SC core which was produce by the first step of drawing, the second 9 MF wire with nine multifilament wire of 0.175mm diameter for each filament,while the 81MFC wire filament diameter was about 25μm for each filament measured with an optical microscope. All the three types of wires were with same outer diameter of 0.9mm. Tc critical temperature for superconductivity is measured for the pellet and wires using four point probes techniques. The critical temperature for the pellet is 110 °K, for the monofilament MOF is 112.5 °K and for 9 filaments 9MF was found is 117°K; while the Tc the 81MF was 119.5°K. The critical current density for the 9MF and 81MF wires were found higher than that of the monofilament MOF in spite of the smaller filament diameters of the 9 MF and 81MF. X-ray diffraction pattern shows the high Tc phase of B2223 compounds in addition to low phase, of B2212 compounds. The I-V curves for the three different wires show higher current density for 81 MF wire, while the optical microscope picture shows more grains alignment . MOC and 9 MF wires show misalignment grains.

YBCO Superconductor Wire based on IBAD-Textured Templates and RCE of YBCO: Process Economics

High-temperature superconductor wire based on the YBa2Cu3Oy compound offers unprecedented performance that stands well above any other superconductor in terms of temperature and magnetic field of operation. We discuss a cost estimate model for production of coated conductors based on ion-beam–assisted deposition (IBAD) of MgO and reactive co-evaporation (RCE) of YBCO. Our results indicate that cost of coated conductors can be below $10/kAm already at 5000 km production volume of 4-mm superconductor wire, with 500 A/cm and 2 μm of YBCO. The total Ic /width is a key parameter for cost/performance of the coated conductor.

Fast insertion impedance of 2G HTS superconductors for megawatt AC and repetitive pulsed power operation

Within the past few years a newer, more robust type of superconductor known as 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> Generation (2G) High Temperature Superconductors (HTS) wire capable to operate in LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> has become available in sufficient quantity and lengths for developers to build prototype devices and test their capabilities. 2G HTS made possible to reduce size, weight and volume of electrical apparatus in few orders of magnitude and provide a fast switching power and energy transitions with negligible impedance in superconducting stage and fast transitions impedances in resistive stage. This transition is typically called quenching and is useful for driving high impedance loads, limiting fault currents and developing large steep insertion impedances useful in many pulsed power applications. Electrical equipments made out of copper or aluminum typically shows high current transitions, inrush and short circuiting faults currents that can reach 100's of kA. There is a need for having repeatable fast insertion impedance to transform high current transitions, useful for impedance matching, stabilization, robustness of large current transients and proper dielectric operation in Megawatt installations. Development of Superconducting Fault Current Limiters (SFCLs) has been pursued for decades and has been limited thermally and/or mechanically by the available superconducting materials performance characteristics. However, this new 2G material has re-invigorated the worldwide race to develop a successful SFCL device that meets the stringent demands of Megawatt power equipment. SuperPower is pursuing the development of modular SFCL based on its proprietary 2G HTS wire and SFCL technologies. We will discuss testing and improvements made to optimize Recovery Under Load (RUL) performance. We also discuss high power tests and the influence of the different variables that have an important impact in RUL. A wide operating RUL window has been tested in order to define where RUL is feasible. We will show the manufacturing and latest tests and capabilities of sub-cooled of the SFCL device and modules designed for distribution and transmission lines. We show the advantages and superior performance of the new 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> Generation HTS superconductors under sub-cooled liquid nitrogen operation when used in SFCL.

Materials Chemistry and the Development of Practical High Temperature Superconductor Wires and Electric Power Applications

not Available.

Electric power grid application requirements for superconductors

Abstract

Performance of 2G HTS Tapes in Sub-Cooled LN2 for Superconducting Fault Current Limiting Applications

Within the past few years a newer, more robust type of superconductor known as 2nd Generation High Temperature Superconductor (HTS) wire, has become available in sufficient quantity and lengths for developers to build prototype devices and test their capabilities. This new material offers the potential for revolutionary changes in superconducting transformers and Super conducting Fault Current Limiters to enable better thermal stability and fast quenching capabilities that can meet the stringent demands of large transient faults for distribution and transmission power lines. This manuscript discusses the manufacturing and latest tests and capabilities of sub-cooled superconducting fault current limiter device and modules designed for distribution and trans mission lines. We will also discuss the advantages and superior performance of the new 2nd Generation HTS superconductors under sub-cooled liquid nitrogen operation when used in super conducting fault current limiters. The feasibility demonstration and performance of sub-cooled SFCL superconducting modules for distribution and transmission SFCL devices will be discussed.

Full Vector Magnetic Field Critical Current Characterization of Coated Conductors Deposited on Solution Deposition Planarized IBAD Templates

Second generation high temperature super-conductor (HTS) wire consists of metal substrate tapes textured with intermediate buffer layers that are coated with a superconducting layer. The applications of these coated conductors require a high current in magnetic fields that are not restricted to a narrow range of angles. Ion beam assisted deposition (IBAD) template tilt, in combination with REBCO vapor deposition, results in asymmetric sample growth. This requires Vector Magnetic Field (VMF) measurement over 180 degrees to be fully described. We have developed a piece wise characterization and analysis method of the VMF using a number of Ic scaling models. Solution Deposition Planarization (SDP) permits REBCO film deposition on 100 nm rms roughness substrates. To test buffer layer effects on film growth, with and without SDP, superconducting films were deposited at Superconductor Technologies, Inc. by co-evaporation of REBCO on IBAD buffer layer templates from Los Alamos. Critical current measurements in VMF up to a magnitude of ~ 0.9 Tesla show behaviors traceable to the effects of buffer layer template on pinning. The ability to discriminate between buffer layers based on in-field Ic behavior is a useful technique for the optimization of buffer layers for future REBCO film deposition.

${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7-\delta}$ Films Grown on Faceted Sapphire Fiber

There have been great advancements in the 2nd generation (2G) high temperature superconductors (HTS) wires termed coated conductors (CCs). Nevertheless, due to the high aspect ratio and the nature of metallic substrates, AC loss is a serious problem for the coated conductors. In this paper, we present a novel approach of fabrication of thin faceted sapphire fibers as substrates for YBCO film growth by laser heated pedestal growth (LHPG) technology. Single crystal sapphire fibers of about 100 μm in diameter with two r-plane facets on the sides have been successfully grown. By adjusting seed orientation and process optimization, the growth was tuned to the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</i> -axis growth with extremely smooth r-plane on the sides. A buffer layer of about 30 nm was then deposited by magnetron sputtering followed by the superconductor layer of YBCO film. A critical current density over 1 MA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> has been demonstrated at 77 K self-field. Experimental results shows that fiber orientation and surface smoothness are critical for the performance of YBCO films and that can be achieved by the technologies presented.